The invention relates to an apparatus for loading and unloading film cassettes and particularly X-ray film cassettes.
The German Offenlegungsschrift 26 07 876 discloses an apparatus provided with a compartment for receiving a cassette, transport means for introducing and discharging the cassette, means for light-tight closing of the cassette means for removing a respective film sheet from the cassette and for transferring the film sheet to a transport roller pair, means for loading a new film sheet into the cassette and a transverely moving shifting device for positioning the cassette and provided with a feeler device for determining the length of the cassette.
According to this reference, the cassette is moved in the compartment to a stop member and then is pushed transversely to the movement against a second lateral stop member by the shifting device. Consequently the cassette is fixed with an edge thereof as reference point.
The shifting device is provided with feelers which engage on one side of the cassette. Through abutment of the shifting device on the cassette, these feelers are actuated i.e. the actuated feelers transmit the information about the cassette length. This apparatus inherents, however, the disadvantage that the provision of a determination solely of the length is insufficient because only one dimension is recognized. Moreover, the apparatus does not allow to determine when a cassette is introduced in a reversed position or when turned about 90.degree..